Definition
AdSense reports impression RPM as estimated earnings per 1,000 ad impressions, alongside page RPM in the same report table Google AdSense Help2026-08. One pageview with four filled ad units generates one pageview and four impressions, so the two RPMs describe the same revenue at different zoom levels.
The connecting arithmetic
page RPM = impression RPM × ad units per page × fill rate
$1.50 impression RPM × 5 units × 80% fill = $6.00 page RPM
check: 1,000 pageviews → 4,000 filled impressions → 4 × $1.50 = $6.00
Fill rate is the share of requested ad slots that actually served a paying ad. It is the quiet variable: adding a sixth ad unit raises the units term but usually lowers both fill and the per-impression price, because the marginal slot sits lower on the page and attracts weaker bids.
When the two RPMs disagree, and what it signals
- Impression RPM up, page RPM down: you are serving fewer but better-priced impressions, often after removing low-value slots. Total revenue decides whether it was a good trade.
- Impression RPM down, page RPM up: you added inventory; each impression earns less, each page earns more. Watch user experience metrics before celebrating.
- Both down: demand fell. Check season first: why did my RPM drop.
Which dashboards report it
AdSense and Google Ad Manager expose impression-level RPM Google AdSense Help2026-08; managed networks generally lead with their aggregate basis instead, session RPM at Mediavine and EPMV at Ezoic Ezoic2026-08. When auditing a managed network's performance, ask for the impression-level export: it is where layout decisions become visible. The full basis comparison lives on the session RPM page.